from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The condition or quality of being external or externalized.
  • n. Something that is external.
  • n. An incidental condition that may affect a course of action: "Our economic system treats environmental degradation as an externality—a cost that does not enter into the conventional arithmetic that determines how we use our resources” ( Barry Commoner).

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The state of being external or externalized.
  • n. A thing that is external relative to something else.
  • n. An impact, positive or negative, on any party not involved in a given economic transaction or act.

from the GNU version of the Collaborative International Dictionary of English

  • n. State of being external; exteriority.

from The Century Dictionary and Cyclopedia

  • n. The state of being external.
  • n. Superficiality.
  • n. An external; an outward rite, ceremony, or form.
  • n. Undue regard to externals; the sacrifice of substance to form.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the quality or state of being outside or directed toward or relating to the outside or exterior


Sorry, no etymologies found.


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  • In an efficient free market, any factor not encapsulated in the price mechanism is an "externality". e.g. the pollution produced by a firm (negative externality), the pollination of a neighbouring orchard by bees (positive externality).

    September 24, 2007

  • basically, an eternality is any third party the corporation can get to pick up the liabilities accrued by the corporation --- generally the public. In this way, the corporation gets the profits but the public gets the losses.

    January 2, 2007